This invention relates to electrochemical storage cells such as a nickel-hydrogen storage cell, and, more particularly, to the support structure for the cell.
Rechargeable cells or batteries are electrochemical energy storage devices for storing and retaining an electrical charge and later delivering that charge as useful power. Familiar examples of the rechargeable energy storage cell are the lead-acid cell used in automobiles, and the nickel-cadmium cell used in various portable electronic devices. Another type of energy storage cell having a greater storage capacity for its weight is the nickel oxide/pressurized hydrogen energy storage cell, an important type of which is commonly called the nickel-hydrogen energy storage cell and is used in spacecraft applications. The weight of the spacecraft energy storage cell must be minimized while achieving the required performance level, due to the cost of lifting weight to earth orbit and beyond.
The nickel-hydrogen energy storage cell includes a series of active plate sets which store an electrical charge electrochemically and later deliver that charge as a useful current. The active plate sets are packaged within a hermetic pressure vessel that contains the plate sets and the hydrogen gas that is an essential active component of the energy storage cell. Each plate set includes a positive electrode, a negative electrode, and a separator between the two electrodes, all soaked with an electrolyte. In a typical energy storage cell, a number of plate sets are supported on a core under a compressive loading, with a gas screen between each plate set and with electrical connector leads extending to each electrode of each plate set. The gas screen provides a gas channel from the hydrogen electrode to the gas space outside the stack. A single nickel-hydrogen energy storage cell delivers current at about 1.3 volts, and a number of the energy storage cells are usually electrically interconnected in series to produce current at the voltage required by the systems of the spacecraft.
Electrical current is delivered from the exterior of the energy storage cell to the plate sets during charging, and delivered from the plate sets to the exterior of the energy storage cell during discharging. The electrical path is through individual leads extending to terminals in the cell wall, and thence to external electrical interconnects. Heat produced in the active plate sets during the electrochemical charging/discharging cycle is removed through the peripheries of the plate sets to the pressure vessel wall.
This approach is well proven and widely used in a variety of spacecraft applications. However, there is always a need to reduce the weight of the battery if possible, with improved performance or at least without loss of performance. The present invention fulfills this need, and further provides related advantages.